Rotary piston pump with retractable cam sealing elements



E April 1967 G. H. DRUTCHAS ETAL 3,314,368

ROTARY PISTON PUMP WITH RETRACTABLE CAM SEALING ELEMENTS Filed Aug. 20, 1965 2 sheets-sheet:

. INVENTORS Gage-e7 H @zura/ms #ueser M 6246K ATTORNEYS A ril 18, 1 61 G. H. DRUTCHA Em 3,314,368

ROTARY PISTON PUMP WITH RETRACTABLE CAM SEALING ELEMENTS Filed Aug. 20. 1965 Z Sheets-Sheet 2 wow-LE7 I 5/ v 5 /6 /3 k if r F 6/ 4 1 49 50 L L L P1 5 4 38/MA%W \5 WA V g INVENTORS G/Qssr A Devin/4s /0856? M (242% xw d E g ATTORNEYS United States Patent ROTARY PISTON PUMP WITH RETRACTABLE CAM SEALING ELEMENTS Gilbert H. Drutchas and Hubert M. Clark, Birmingham,

Mich., assignors to TRW Inc., Cleveland, Ohio, a corporation of Ohio Filed Aug. 20, 1965, Ser. No. 481,222 4 Claims. (Cl. 103123) This invention relates generally to methods and apparatus of pumping or motoring fluids of any type and more particularly relates to a rotary piston pump with retractable cam sealing elements wherein a rotary piston having two movable sealing points slidably engaging the walls of a circular pumping chamber is, in turn, sealed by two slidably retractable cams which may be pres sure loaded into sealing engagement with the rotary piston, thereby to successively expand and contract the volume of pumping spaces formed between the respective cams, which pumping spaces are portedthrough the rotary piston.

It is an object of the present invention to provide an improved rotary piston pump.

Another object of the present is to provide a rotary piston pump with retractable c'am sealing elements which are pressure-biased by fluid at pump-generated pressures.

Still another object of the presentinvention is to provide a rotary piston pump wherein a fixed commutation pintle forms a portion of the inlet passage and inlet fluid is conducted from the pintle to the pumping chamber via the rotary piston.

A still further object of the present invention is to provide a rotary piston pump wherein fluid is discharged through a side porting arrangement and at least a portion of the discharge passages are formed in the rotary piston of the pump.

Many other features, advantages and additional objects of the present invention will become manifest to those versed in the art upon making reference to the detailed description which follows and the accompanying sheets of drawings in which a structural embodiment of the present invention is shown byway of illustrative example.

On the drawings:

FIGURE 1 is a somewhat schematic view of a rotary piston pump with retractable cam se'aling elements as provided in accordance with the principles of the present invention;

FIGURE 2 is a view of the pump of FIGURE 1 Show ing the opposite side of the pumping construction;

FIGURE 3 is a fragmentary cross-sectional view taken generally'on line III-III of FIGURE 1;

FIGURE 4 is a fragmentary cross-sectional view taken generally on line IV-IV of FIGURE 1;

FIGURE 5 is an elevational view of the rear header incorporated in the pump of the present invention and showing additional details of construction of the pintle arrangement included in the pump; and

FIGURE 6 is an exploded view showing additional details of construction of the pump and showing the header of FIGURE 5 from the opposite side.

As shown on the drawings:

The pump of the present invention is shown generally at 10 and comprises a casing 11 in which is formed a pumping bore of circular configuration 12.

A pintle shown generally at 13 has a bearing portion 14 projecting into the pumping bore 12 and a bearing ,hub portion of a rotor shown generally at 18. The rotor 18 has an irregular peripheral surface 19 which is ice characterized by a pair of circumferentially spaced sealing areas located in diametrically opposed relation to one another and shown at 20 'and 21, respectively. Thus, when the rotor 18 is rotated Within the pumping bore 12, the sealing areas 20 and 21 Will slidably engage the adjoining wall of the pumping bore 12 in sealing relation therewith.

The casing 11 is further characterized by 'a pair of slots 22 and 23 which extend outwardly of the pumping bore 12 in generally parallel relation to one another and in a chordal relation relative to the circular pumping bore 12. Each of the slots 22 and 23 includes spaced apart side walls which terminate in a bottom wall shown at 24 and 26, respectively.

A retractable cam member 27 is located in each respective cam slot 22 and 23 and since the cam members are of identical construction, like reference numerals will be used to identify like parts.

Each cam member 27 is generally of rectangular configuration including longitudinally spaced end walls 28, side walls 29, 29 and a bottom wall which forms a motive surface 30. The motive surface 30 is spaced from the bottom wall 26 at the bottom of the slot 22 or 23, thus to form a pressure control chamber 31.

The portion of the cam 27 projecting into the pumping chamber 12 constitutes a curved cam action surface 32, thereby to slidably engage the peripheral surface 19 of the rotary piston 18 in sealing relationship therewith.

A continuous biasing means which may conveniently take the form of a coil spring 33 is located in each respective slot 22 and 23 and has one end bottomed against the motive surface 30 and the other end bottomed against the corresponding bottom wall 24 or 26 of each corresponding slot '22 and 23, thereby to preload the cams 27 into sealed relation with the rotary piston 18. I

In order to afford pressure loading of the cam members 27, the casing 11 is formed with a passage 34 communicating with the pumping chamber 12 as at 36 and opening into the bottom portion of the slot at 37. Thus, fluid at pump-generated pressure will be conducted into the pressure control chambers 31 and the pressure will thus be exerted against the motive surface 30 to pressure-load the cams 27 into sealing relation with the rotary piston 18.

The pintle 13 is hollow thereby forming an 'axial inlet passage 38 and the bearing portion 14 is characterized by radially outwardly extending inlet ports 39, 39. The inlet ports 39, 39 in the pintle 13 communicate with inlet passages formed in the rotary piston 18 and which are shown at 40. Each of the passages 40 extends generally radially outwardly and it will be noted that each passage 40 opens out of the peripheral surface 19 of the rotary piston 18 as at 41 on one circumferential side of the corresponding sealing areas 20 and 21, respectively.

The rotary piston 18 is also formed'with discharge passages more clearly shown in FIGURE 2 and the discharge passages are shown at 42 and extend inwardly from a location 43 on the opposite circumferential side of the respective sealing areas 20 and 21 inwardly towards a common area 44 in register with a kidney-shaped side outlet port 46 formed in an adjoining wall of the casing 11.

By virtue of such provision, when the rotary piston 18 is rotated in the direction of the arrow 47, it will act to successively expand and contract the volume of the pumping spaces between the respective cams 27 and the respective sealing areas 20 and 21. Accordingly, fluid will be drawn in through the inlet passages 40, the ports 39, 39, and the axial inlet passage 38 and the pintle 13. When compressed through rotative action of the rotary piston 18, the pressurized fluid will be discharged through the passage 42 and the port area 44 into the outlet port 46 for direction to a point of utilization.

In order to provide a rotatable driving connection for the rotary piston 18, the hub portion of the rotary piston 18 is formed with a spline coupling 48 which cooperates with a corresponding spline 49 in a shaft 50.

As shown in FIGURES 3 and 4, the hub portion of the rotary piston 18 has two separate recesses formed therein, one recess being shown at 51, thereby to form a bearing surface 52 for journaling relationship on the bearing surface 16 of the bearing portion on the pintle 13 and the other recess being shown at 53 for the purpose of forming the splined coupling 48.

The structural characteristics of an actual commercial embodiment of the pump thus far described is shown in FIGURES 5 and 6 and it will be noted that the casing 11 is shown therein as constituting three separate parts including a center section 11a, a rear header 11b and a so-called housing bushing assembly 11c.

In FIGURE 5, the structural configuration of the pintle 13 is particularly clear and there it will be noticed that the inlet ports 3-9 communicate with the axial inlet passage 38 to direct the inlet fluid through the bearing surface 16 directly into the inlet passages 40 formed in the rotary piston 18. The rear header 11b has a radial face 54 which closes one side of the pumping chamber 12 and the bearing portion 14 of the pintle 13 projects from the face 54 into the pumpingchamber 12.

The housing bushing assembly also provides a radial face 56 which closes the other side of the pumping chamber 12 and it is in the face 56 that the outlet port 46 is formed. A passage extending through the housing bushing assembly 110 directs the fluid to a discharge outlet 57 and such passage is shown in FIGURE 4 at 58. All of the casing components 11a, 11b and 11c are suitably apertured as at 60 so they may be fastened together in integral relationship with one another. The housing bushing assembly 11c is also provided with a sleeve bearing 61 in order to provide a bearing support for the shaft 50.

In the view of FIGURE 1, the pump is at dead center and full fill, no pressure condition. has flowed from the stationary commutation pintle 13 through the axial eye passage 38, through the radial ports 39, 39 in the pintle 13 intersecting the bearing surface 16 and thence through the inlet passages 40, 40 of the rotary piston *18 into the displacement cavities of the pumping chamber 12. Since the pasages 40, 40 are on the bottom face of the rotor or rotary piston 18 relative to the sealing surfaces 20 and 21, intake fluid will flow upon rotation of the rotor into the pumping cavities since the pumping cavities are expanding relative to the retractable cams 27, 27.

In the view of FIGURE 2, the rotor or rotary piston 18 has passed to a midway position in its stroke and the pumping cavities in communication with the inlet passages 40 are again increasing while the pumping cavities in communication with the outlet passages 42 are under compres sion. The under side of the earns 27, 27 are pressureenergized through the passages 34, thereby holding the sealing engagement between the cam action surfaces 32 and the peripheral surface 19 of the rotor or rotary piston. Thus, fluid at increased pressure will flow from the compression cavities through the passages 42, 44 and into the outlet port 46. From the port 46, the fiuid is discharged through the passage 58 and the discharge outlet 57.

Although minor modifications might be suggested by those versed in the art, it should be understood that we wish to embody within the scope of the patent warranted hereon all such modifications as reasonably and properly come within the scope of our contribution to the art.

We claim as our invention:

1. A pump comprising:

a casing including:

a center section, a rear head nd The pumping fluid a housing bushing assembly,

said center section having a generally circular pumping chamber formed therein, said center section further including at least a pair of diametrically opposed slots extending outwardly of said pumping chamber in parallel chordal relation thereto,

a rotary piston in said pumping chamber having an irregular peripheral surface characterized by two circumferentially spaced sealing areas slidably sealing against the adjoining wall of said pumping chamber upon rotation therein,

a retractable cam in each of said slots having a motive surface spaced from the adjoining bottom wall of the corresponding slot to form a pressure control chamher and having a curved cam action surface projecting out of said corresponding slot to slidably seal against said peripheral surface of said rotary piston,

a coil spring bottomed in each slot and engaging said motive surface of the corresponding cam to preload the cam into engagement with said rotary piston,

passage means in said casing between said pumping chamber and the bottom of each said slot to conduct fluid at p ump-generated pressure into said pressure control chambers to pressure-load said cams into sealing relation with said rotary piston,

said rear header having a side face for closing one side of said pumping chamber,

a pintle in said rear header having a bearing portion projecting into said pumping chamber,

said pintle having a hollow interior forming an inlet passage and including radial inlet ports in said bearing portion,

said rotary piston having a bearing recess formed therein for journaling said rotor on said bearing portion of said pintle and a pair of radially outwardly extending inlet passages opening into said pumping chamber on one circumferential side of each corresponding one of said sealing areas,

thereby to conduct pumping fluid into the pumping chamber,

said housing bushing assembly having a side face for closing the other side of said pumping chamber and being characterized by an outlet port formed therein,

said rotary piston having outlet passages extending inwardly from the other circumferential side of said sealing areas and opening out of the side of said rotary piston for discharging through said outlet port,

a discharge outlet on said housing bushing assembly receiving the fluid fromv said outlet port,

and a shaft journaled in said housing bush-ing assembly and having a driven connection with said rotary piston to rotatably drive said rotary piston.

2. A pump comprising a casing having a generally circular pumping bore formed there-in,

a hollow pintle in said casing having a bearing portion projecting into said pumping bore,

a rotor journalled on said bearing portion having a peripheral surface of irregular configuration and including a sealing area for slidably engaging and seal-ing against the adjoining wall of said bore,

said bearing portion having an inlet port extending radially outwardly and said rotor having inlet passage means formed therein to conduct inlet fluid from the hollow interior of said pintle into said pump-ing bore,

and a continuously biased retractable cam sealing means in said casing having an action surface projecting into said bore for slidable sealing contact with said peripheral surface of said roto-r,

said casing having a side discharge port adjacent said rotor and said rotor having a discharge passage means therein for conducting fluid at increased pressure to said discharge port,

means forming a pressure control chamber behind said cam means, and

said cam means having a motive surface in said pressure control chamber,

and passage means to conduct fluid at pump-generated pressure into said pressure control chamber behind said cam sealing means to pressure-load said motive surface and thereby urge said cam sealing means into sealing relationship with said rotor.

3. In a rotary piston pump, the improvement of a casing having an inlet and an outlet and a generally circular pumping chamber formed therein,

said pumping chamber being intersected by a pair of circumferentially spaced slots extending outwardly of said pumping chamber and formed in said casing,

a rotary piston in said pumping chamber having an irregular peripheral surface including a pair of circumferentially spaced sealing areas slidably engaging the adjoining Wall of said pumping chamber in sealing relation for pumping fluid from the inlet to the outlet,

and a retractable cam in each said slot and each having a curved cam action surface to slidably engage said peripheral surface of said rotary piston,

and a spring preloading each cam outwardly of the slot,

thereby to develop a pumping action upon rotation of the rotary piston,

means forming a pressure control chamber in said casing behind each said cam,

and passage means formed in said casing for conducting fluid at pump generated pressure from said pumping chamber to said control chambers to pressure load said cams into sealing relation with the rotary piston.

4. In a rotary piston pump, the improvement of a casing having an inlet and an outlet and a generally circular pumping chamber formed therein,

said pumping chamber being intersected by a pair of circumferentially spaced slots extending outwardly of said pumping chamber and formed in said casing,

a rotary piston in said pumping chamber having an irregular peripheral surface including a pair of circumferentially spaced sealing areas slidably engaging the adjoining Wall of said pumping chamber in sealing relation for pumping fluid from the inlet to the outlet, and a retractable cam in each said slot and each having a curved cam action surface to slidably engage said peripheral surface of said rotary piston, and a spring preloading each cam outwardly of the slot, thereby to develop a pumping action upon rotation of the rotary piston,

21 pintle having a bearing portion,

said piston having a hub forming a bearing surface for journalling said rotary piston on said bearing portion of said pintle, said pintle being ported to form an inlet passage opening at said bearing portion, said piston having inlet passages opening out of said periphery and out of said bearing surface, said casing having an outlet including a port adjacent said rotary piston, said piston having outlet passages formed therein opening out of said periphery in spaced relation to said inlet passages and opening out of the side of said rotary piston to direct pressurized fluid into said outlet p means forming a pressure control chamber in said casing behind each said cam, and passage means for conducting fluid at pump generated pressure from said pumping chamber to said control chambers to pressure load said cams into sealing relation With the rotary piston.

References Cited by the Examiner UNITED STATES PATENTS 129,703 7/1872 Allen 91-105 381,287 4/1888 Snevely 91l05 713,448 11/1902 Kalbach 91-105 832,848 10/1906 Croston 91104 2,232,951 2/1941 Kosian 103-123 3,016,019 1/1962 Rineer 103123 FOREIGN PATENTS 978,151 11/1950 France. 3 05,990 5/ 1918 Germany.

11,548 1904 Great Britain.

DONLEY J. STOCKING, Primary Examiner. WILBUR I. GOODLIN, Examiner, 

1. A PUMP COMPRISING: A CASING INCLUDING: A CENTER SECTION, A REAR HEADER, AND A HOUSING BUSHING ASSEMBLY, SAID CENTER SECTION HAVING A GENERALLY CIRCULAR PUMPING CHAMBER FORMED THEREIN, SAID CENTER SECTION FURTHER INCLUDING AT LEAST A PAIR OF DIAMETRICALLY OPPOSED SLOTS EXTENDING OUTWARDLY OF SAID PUMPING CHAMBER IN PARALLEL CHORDAL RELATION THERETO, A ROTARY PISTON IN SAID PUMPING CHAMBER HAVING AN IRREGULAR PERIPHERAL SURFACE CHARACTERIZED BY TWO CIRCUMFERENTIALLY SPACED SEALING AREAS SLIDABLY SEALING AGAINST THE ADJOINING WALL OF SAID PUMPING CHAMBER UPON ROTATION THEREIN, A RETRACTABLE CAM IN EACH OF SAID SLOTS HAVING A MOTIVE SURFACE SPACED FROM THE ADJOINING BOTTOM WALL OF THE CORRESPONDING SLOT TO FORM A PRESSURE CONTROL CHAMBER AND HAVING A CURVED CAM ACTION SURFACE PROJECTING OUT OF SAID CORRESPONDING SLOT TO SLIDABLY SEAL AGAINST SAID PERIPHERAL SURFACE OF SAID ROTARY PISTON, A COIL SPRING BOTTOMED IN EACH SLOT AND ENGAGING SAID MOTIVE SURFACE OF THE CORRESPONDING CAM TO PRELOAD THE CAM INTO ENGAGEMENT WITH SAID ROTARY PISTON, PASSAGE MEANS IN SAID CASING BETWEEN SAID PUMPING CHAMBER AND THE BOTTOM OF EACH SAID SLOT TO CONDUCT FLUID AT PUMP-GENERATED PRESSURE INTO SAID PRESSURE CONTROL CHAMBERS TO PRESSURE-LOAD SAID CAMS INTO SEALING RELATION WITH SAID ROTARY PISTON, SAID REAR HEADER HAVING A SIDE FACE FOR CLOSING ONE SIDE OF SAID PUMPING CHAMBER, A PINTLE IN SAID REAR HEADER HAVING A BEARING PORTION PROJECTING INTO SAID PUMPING CHAMBER, SAID PINTLE HAVING A HOLLOW INTERIOR FORMING AN INLET PASSAGE AND INCLUDING RADIAL INLET PORTS IN SAID BEARING PORTION, SAID ROTARY PISTON HAVING A BEARING RECESS FORMED THEREIN FOR JOURNALING SAID ROTOR ON SAID BEARING PORTION OF SAID PINTLE AND A PAIR OF RADIALLY OUTWARDLY EXTENDING INLET PASSAGE OPENING INTO SAID PUMPING CHAMBER ON ONE CIRCUMFERENTIAL SIDE OF EACH CORRESPONDING ONE OF SAID SEALING AREAS, THEREBY TO CONDUCT PUMPING FLUID INTO THE PUMPING CHAMBER, SAID HOUSING BUSHING ASSEMBLY HAVING A SIDE FACE FOR CLOSING THE OTHER SIDE OF SAID PUMPING CHAMBER AND BEING CHARACTERIZED BY AN OUTLET PORT FORMED THEREIN, SAID ROTARY PISTON HAVING OUTLET PASSAGES EXTENDING INWARDLY FROM THE OTHER CIRCUMFERENTIAL SIDE OF SAID SEALING AREAS AND OPENING OUT OF THE SIDE OF SAID ROTARY PISTON FOR DISCHARGING THROUGH SAID OUTLET PORT, A DISCHARGE OUTLET ON SAID HOUSING BUSHING ASSEMBLY RECEIVING THE FLUID FROM SAID OUTLET PORT, AND A SHAFT JOURNALED IN SAID HOUSING BUSHING ASSEMBLY AND HAVING A DRIVEN CONNECTION WITH SAID ROTARY PISTON TO ROTATABLY DRIVE SAID ROTARY PISTON. 